A Doherty amplifier, which dynamically changes the number of amplifiers in accordance with the amplitude of a high-frequency input signal, is known. The Doherty amplifier is configured with one main amplifier and one or more number of peak amplifiers. A Doherty amplifier having an N number of amplifiers is referred to as an N-way Doherty amplifier. The main amplifier always operates, and the peak amplifiers operate only with great power. Although a 2-way Doherty amplifier having one peak amplifier is popular, there is a Doherty amplifier having two or more peak amplifiers. Each amplifier uses a transistor (bipolar, FET) as an amplification element.